Index A appearance APQ triplet A averages Arago Point aberration arclet , , –annual arcs , –constant area measurement –diurnal area number , –ofstarlight –Beck absolute magnitude armillary sphere Absorption Av ASCOM achromat ASCOM driver active galaxy , , , Association of Lunar and Planetary Observers active nuclei , active solar regions asteroid , activity center , –absolutemagnitude –development – asteroid family activity cycle –lightcurve activity herd –oppositioneffect adaptive Laplace filtering , –phasefunction afocal – polarimetry air mass –spectroscopy Airy disk –visualbrightness albedo Asteroid Belt Alt-Azimuthal asteroid profile amateur asteroid-like appearance –astronomer asteroid-like comet –observer astigmatism – working group astrometric data reduction amateur–professional partnership , astrometry of asteroids American Association of Variable Star Observers astronomical education , , –hands-onastronomy –SolarDivision – in the classroom Andromeda Nebula –planetarium () Annefrank , – public observatory annular eclipse , , , – science museum annular/total eclipse – societies and organizations anti-tail , astronomical research antireflection coating astronomical societies aperture photometry Astronomical Society of the Pacific aperture stop astronomy aphelion astronomy day () APL , astronomy olympiad apochromat astronomy vacation , Apollo astrophotography Apollo shock asymptotic (or second) giant branch (AGB) apparition light curve atmosphere of the Earth Index atmospheres of asteroids binoculars atmospheric dispersion bipolar Atmospheric Dispersion Corrector BL-Lac atmospheric optics BL-Lac object atmospheric turbulence black body aurora , black drop , – auroral oval black drop effect – observability black filters – photographic observations black hole autoguiding blaze grating automatic control blindness automatic gain control (AGC) block filter autumnal equinox blue loop averted vision BNC jack , –visualobservation P/Boethin azimuth bolides bolometric correction B bolometric magnitude Boltzmann equation Babinet Point P/Borrelly baffles P/Borrelly , Baily’s beads , – () Braille ball bearing Brewster Point Balmer lines , , brightness Balmer series , , brightness characteristic , Balmer spectral line brightness curve band drive brightness distribution Barlow lens brightness outbursts Be stars British Astronomical Association bearing brown dwarfs Bernhard Schmidt butterfly diagram , Big Bang binary stars C –catalogue – close binary C/ O Hale–Bopp , – contact system C/ B Hyakutake – eclipsing binary , , Ca II K line – eclipsing variable calcium II – ellipsoidal stars calibration – ellipsoidal variable –bias – high-mass X-ray binary –flat-field –history –fluxstandard – low-mass X-ray binary –intensity – orbit , – wavelength – orbital element camera –over-contactsystem carrington rotation –radialvelocity Carte du Ciel – reflection variable cassegrain – RS Canum Venaticorum stars Cassini , – RS Canum Venaticorum system cataclysmic variable – semidetached system catadioptric system –spectroscopicbinary catoptric system –structure CCD (charge–coupled device) , , , – Thiele-Innes element , – visual binary , , CCD camera , , Index CCTV –astrometry celestial – coma appearance –equator , – coma photometry – poles –cometformation –sphere – comet reservoir Centaurs objects , –cometsplitting center line , – comet-like object central bulge – cometary coma central flash – cometary tails central meridian – composition () Ceres –, , –discovery Charge-coupled devices – dust production Cheshire –dusttails , Cheshire “eyepiece” – dynamical classes () Chiron – ephemerides chromatic aberration –findingcharts chromatic error –interior chromosphere , , , , –iontails chromospheric activity – naming convention chromospheric network –neutralgastail chromospheric phenomena – nucleus P/Churyumov–Gerasimenko , – nucleus size circumpolar , –numberingscheme circumstellar (CS) material – optical characterization classical disk objects – orbit determination classification –orbitpredictions – of galaxies –organiccompounds –scheme – peculiar comet –system – polarimetry classification values –rotation clouds , – rotation light curves cluster of galaxies , –searches CMOS – space missions Coaxial cable –spectroscopy coded-angle encoder – sublimation collimating , – surface morphology collimation –visualbrightness collimation tools comet brightness collision family , comet splitting events –Eosfamily cometary nuclei –Flora cometary orbit – Koronis Committee of Space Research –Themis condensation degree color index contact , color slide film – second , , color-magnitude diagram – third , , coma , contacttime ,,,,,,, coma activity , coma brightness CONTOUR comatic error cool stellar wind Comet –coolwind comet ,,,,, coordinate , , , –, –activity –altitudeabovesealevel –Afρ – converter/calculator –albedo – ecliptic Index – galactic , differential refraction – geographic latitude differential rotation , – geographic longitude diffraction , – horizontal diffraction grating Copernican system diffuse reflection , core collapse digital camera , corona , , , , – digital multimeter – K-corona digital position display – L-corona digital SLRs – photospheric light dioptric system coronal mass ejections direct marking technique coronograph direct-vision prism cosmic cycle disconnection events cosmic radiation dispersion –, cosmology distance indicator Coudé focus distortion , counterglow Dobson, J. crater time Dobsonian CS shell Doppler effect , , Cubewanos , dormant Cusp extension , Dorpat refractor cylindrical projection dry plate DSLRs D dust coma –gascoma D/ F Shoemaker–Levy , dust striae Dactyl , dust tail , , damage dwarf galaxies –eye dwarf planet Danjon scale , dark halo E dark matter , dark-sky Earth – daughter species – apparent horizon Dawes criterion – atmosphere Dawes formula –equator ,, Dawn mission , –equatorialplane day – Greenwich , –mean – horizon , , – mean solar –latitude , – sidereal –longitude declination – meridian –axis –nadir – circle – poles deep sky , – reference ellipsoid DEEPIMPACT , – true horizon DEEPSPACE , , –zenith , degree circle – zero meridian density-wave theory Earth’s shadow ,, , , , detached disk of KBOs , detector –color , dewcap –enlargement , dial –penumbral diameters of galaxies – penumbral shadow diamond ring , –umbral ,, Index Ebert mounting –kneemounting eclipse , , , – Springfield mounting –annular , equinoxial dial –brightness equivalent width –color () Eris –eyeglasses () Eros – –greatest error – lunar , , , , , –random –magnitude – systematic –partial eruptive variable –partialsolar , European Radio Astronomy Club –penumbrallunar , European Southern Observatory (ESO) – solar , – , –total European Space Agency –totallunar , evolution –totalsolar – Asteroid belt – totality ,,,,, –Kuiperbelt eclipse eyeglasses , excitation , eclipse magnitude , exit pupil eclipse wind exoplanets eclipsing binary , , exposure time , – β-Lyrae-type extinct comet –Algol-type extinction , , –lightcurve extinction coefficient – light curve analysis extinction E(B–V) – light curve synthesis extinction E(B–V) and absorption (Av) – W Ursae Majoris stars extragalactic object , –WUrsaeMajoris-type extrasolar planet eclipsing variable eye – classification eye damage ecliptic , , eye relief –latitude eye Safety –longitude eyepiece ED glass –designtype Edgeworth–Kuiper Belt –filter effective temperature , –micrometer egress –, , –projection electromagnetic spectrum electronic camera F elliptical – galaxy F-corona –system f-spot ellipticity Fabry–Pérot interferometer () Elst–Pizarro facula activity P/Elst–Pizarro faculae , P/Encke – area-shaped energy equipartition – chromospheric energy source – latitude distribution English mounting – lifetime entrance pupil – photospheric , ephemerides , – point-shaped equatorial mount – polar , equatorial mounting faculae areas – folly mounting fans , –horseshoemounting fiber Index field –“halo” –curvature –latitude –ofview , –longitude –stop – plane , filament galaxy , filar micrometer , GALILEO , , , – measuring procedure Gamma ray bursts filter ,,, gas nebulae – Hydrogen-alpha gas tail –Moon () Gaspra , filter foil , , Gauss finder scope Gegenschein finding General Catalogue of Variable Stars , , –asteroid fireball geocentric system first point of Aries geometrical foreshortening FITS (Flexible Image Transport System) geostationary orbit , Fitswork geostationary satellite , , – flare , geosynchronous orbit flash German mounting flash spectrum , , P/Giacobini–Zinner flattening GIOTTO , fluorescence , Giotto (software) , focal Gleissberg cycle –image globular clusters (GC) – length , , , gnomon –ratio GoTo , – ratio degradation GoTo mounting focal diaphragm GPS device , focus , , GPS receiver , –focusing , GPUSB folded refractor granulation forbidden line grating formation – blaze grating – Asteroid belt – diffraction grating –Kuiperbelt – echelle grating foundation – equation , four-element eyepiece – reflection grating –orthoscopic – replica – Plössl gravitational perturbation – Superplössls Gray Veil fragment